From 1960 to May 1979 245 patients have been operated upon at the National Heart, Lung, and Blood Institute for relief of symptomatic idiopathic hypertrophic subaortic stenosis. Left ventricular myotomy and myectomy was carried out in nine patients with obstructive hypertophic cardiomyopathy solely because of a previously documented episode of cardiac arrest. Prior to arrest, each patient had either no or only minimal functional limitation, and, therefore, would not have met the usual criteria for operation: severe symptoms unresponsive to medical therapy.